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SPP 3.5/3.3 Difference from earlier versions


Well-Known Member

A small difference that can be easily overlooked.
When Clicking "Show warnings", you will see no warnings, unless you change the default values to something else than 0 and 255.
In earlier versions the default values was set otherwise.
What the justification for this change is, I do not know.

kind regards


Well-Known Member
The exposure warning range can be anything you want. I see no problem with the as installed defaults being 0 and 255, since you can set a range which suites your work at the time. The only limitation is that the lower and upper range settings can't overlap.

Here is a question that I'm curious about. Why does SPP use image values in the range from 0 to 255, corresponding to 8 bits per channel, and not 0 to 4095, corresponding to the 12 bit ADCs in the SD14 ?

While at it, when saving 16 bit per channel images, does SPP perform a 4 bit shift, a multiply by 16, or nothing at all leaving the dark yet unaltered to expand the 12 bit ADC data into the 16 bit 0 to 65535 dynamic range ? I hope they perform a bit shift because a multiply would increase the noise. Ideally, I'd prefer they would allow the photographer to choose. For my astrophotography, I could easily live with the upper 4 bits being 0.


Well-Known Member
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Common practice - most image editors show you range 0-255 independent of bit depth. Much comfortable to follow IMHO.

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4bit shift (to left) and multiply by 16 are exactly identical operations :)
But actual processing pipeline is much more complex than just saving raw data, some major possible steps:

1. X3F - linear RGB (or XYZ) colorspace conversion by aggressive matrix (probably different matrices for different ISO and WB settings);
2. Saturation, color, fill light etc etc adjustments in linear color space;
3. Output colorspace conversion from linear to sRGB/Adobe space.

Add there needed linearizations, noise suppression, green corner suppression (and probably many more things, what I'm not aware of) - you don't have any pure raw data on output anyway :)


Well-Known Member
I am curious to know what exposure warning ranges most people use. Under what circumstances do you change them? Do you always change them symmetrically (e.g., +10 blue, -10 red)? Do you just set them once and leave them (like me)?

How can this functionality best be put to use?